Land-Based Wind Market Report: 2021 Edition This Report Is Being Disseminated by the U.S

Total Page:16

File Type:pdf, Size:1020Kb

Land-Based Wind Market Report: 2021 Edition This Report Is Being Disseminated by the U.S Land-Based Wind Market Report: 2021 Edition This report is being disseminated by the U.S. Department of Energy (DOE). As such, this document was prepared in compliance with Section 515 of the Treasury and General Government Appropriations Act for fiscal year 2001 (public law 106-554) and information quality guidelines issued by DOE. Though this report does not constitute “influential” information, as that term is defined in DOE’s information quality guidelines or the Office of Management and Budget’s Information Quality Bulletin for Peer Review, the study was reviewed both internally and externally prior to publication. For purposes of external review, the study benefited from the advice and comments of 11 industry stakeholders, U.S. Government employees, and national laboratory staff. NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at SciTech Connect: http://www.osti.gov/scitech Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 OSTI: http://www.osti.gov Phone: 865.576.8401 Fax: 865.576.5728 Email: [email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5301 Shawnee Road Alexandria, VA 22312 NTIS: http://www.ntis.gov Phone: 800.553.6847 or 703.605.6000 Fax: 703.605.6900 Email: [email protected] ii Land-Based Wind Market Report Preparation and Authorship This report was prepared by Lawrence Berkeley National Laboratory for the Wind Energy Technologies Office of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy. Corresponding authors of the report are: Ryan Wiser and Mark Bolinger, Lawrence Berkeley National Laboratory. The full author list includes: Ryan Wiser, Mark Bolinger, Ben Hoen, Dev Millstein, Joe Rand, Galen Barbose, Naïm Darghouth, Will Gorman, Seongeun Jeong, Andrew Mills, and Ben Paulos. iii Land-Based Wind Market Report Acknowledgments For their support of this ongoing report series, the authors thank the entire U.S. Department of Energy (DOE) Wind Energy Technologies Office team. In particular, we acknowledge Patrick Gilman and Robert Marlay. For reviewing elements of this report or providing key input, we also thank: Christopher Namovicz, Manussawee Sukunta, and Richard Bowers (U.S. Energy Information Administration); Andrew David (U.S. International Trade Commission); Charlie Smith (Energy Systems Integration Group); Feng Zhao (Global Wind Energy Council); David Milborrow (consultant); Anjelaka Stolte (Boston Consulting Group); Matt McCabe (Clear Wind); Eric Lantz (National Renewable Energy Laboratory, NREL); Kelsey Bartz, Brendan Casey, and John Hensley (American Clean Power Association); and Patrick Gilman and Gage Reber (DOE). For providing data that underlie aspects of the report, we thank the U.S. Energy Information Administration, BloombergNEF, Wood Mackenzie, Global Wind Energy Council, and the American Clean Power Association. Thanks also to Donna Heimiller (NREL) for assistance in mapping wind resource quality; Amy Howerton and Carol Laurie (NREL), and Liz Hartman, Coryne Tasca, and Kaitlyn Roach (DOE) for assistance with layout, formatting, production, and communications. Lawrence Berkeley National Laboratory’s contributions to this report were funded by the Wind Energy Technologies Office, Office of Energy Efficiency and Renewable Energy of the DOE under Contract No. DE-AC02-05CH11231. The authors are solely responsible for any omissions or errors contained herein. iv Land-Based Wind Market Report List of Acronyms ACP American Clean Power Association BNEF BloombergNEF BPA Bonneville Power Administration CAISO California Independent System Operator COD commercial operation date CCA community choice aggregator DOE U.S. Department of Energy EIA U.S. Energy Information Administration ERCOT Electric Reliability Council of Texas FAA Federal Aviation Administration FERC Federal Energy Regulatory Commission GE General Electric Corporation GW gigawatt HTS Harmonized Tariff Schedule IOU investor-owned utility IPP independent power producer ISO independent system operator ISO-NE New England Independent System Operator ITC investment tax credit kV kilovolt kW kilowatt kWh kilowatt-hour LCOE levelized cost of energy m2 square meter MISO Midcontinent Independent System Operator MW megawatt MWh megawatt-hour NREL National Renewable Energy Laboratory NYISO New York Independent System Operator O&M operations and maintenance OEM original equipment manufacturer PJM PJM Interconnection POU publicly owned utility PPA power purchase agreement PTC production tax credit v Land-Based Wind Market Report REC renewable energy certificate RPS renewables portfolio standard RTO regional transmission organization SGRE Siemens Gamesa Renewable Energy SPP Southwest Power Pool W watt WAPA Western Area Power Administration WECC Western Electricity Coordinating Council vi Land-Based Wind Market Report Executive Summary Wind power capacity additions in the United States hit a new record in 2020, supported by the industry’s primary federal incentive—the production tax credit (PTC)—as well as a myriad of state-level policies. Improvements in the cost and performance of wind power technologies have also driven wind capacity additions, yielding low-priced wind energy for utility, corporate, and other power purchasers. Key findings from this year’s Land-Based Wind Market Report—which primarily focuses on land-based, utility-scale wind—include: Installation Trends • Wind power capacity grew at a record pace in 2020, with 16,836 MW of new capacity added in the United States and $24.6 billion invested. Cumulative wind capacity grew to 121,985 megawatts (MW). In addition, 3,087 MW of existing wind plants were partially repowered in 2020, mostly by upgrading rotors and major nacelle components of existing turbines. • Wind power represented the largest source of U.S. electric-generating capacity additions in 2020. Wind power constituted 42% of all capacity additions in 2020. Over the last decade, wind represented 29% of total U.S. capacity additions, and an even larger fraction of new capacity in SPP (75%), ERCOT (54%), MISO (52%), and the non-ISO West (32%). [See Figure 1 for regional definitions]. • Globally, the United States ranked second in annual wind capacity additions in 2020, but remained well behind the market leaders in wind energy penetration. Global wind additions hit a record in 2020, with nearly 93 GW of newly added capacity, yielding a cumulative total 743 GW. The United States remained the second-leading market in terms of annual and cumulative capacity, behind China. A number of countries have achieved high levels of wind penetration, with wind supplying nearly 50% of Denmark’s total electricity generation in 2020, and between 25% and 40% in Ireland, Germany, the U.K, and Portugal. In the United States, wind supplied 8.3% of total electricity generation in 2020. • Texas installed the most capacity in 2020 with 4,137 MW, while sixteen states exceeded 10% wind energy penetration as a fraction of total in-state generation. Texas also remained the clear leader on a cumulative basis, with 32,686 MW of capacity. Notably, the wind capacity installed in Iowa supplied 57% of all in-state electricity generation in 2020, while Kansas (43%), Oklahoma (35%), South Dakota (33%) and North Dakota (31%) were all above 30% by this metric. Within independent system operators (ISOs), 2020 wind penetration (expressed as a percentage of load) was 31.3% in SPP, 22.7% in ERCOT, 11.0% in MISO, 6.6% CAISO, 3.4% in the PJM, 3.0% in ISO-NE, and 2.9% in NYISO. • A small but growing number of hybrid plants that pair wind with storage and other resources are operating in the United States. There were 38 hybrid wind power plants in operation at the end of 2020, representing 2.3 GW of wind and 0.9 GW of co-located assets. The most common wind hybrid project combines wind and storage technology, where 1.4 GW of wind has been paired with 0.2 GW of battery storage (14% storage to generator ratio). The average storage duration of these projects is 0.6 hours, suggesting a focus on ancillary services and limited capacity to shift large amounts of energy across time. • Despite a slight contraction since 2018, substantial wind power capacity exists in transmission interconnection queues; solar and storage reached new highs in 2020. At the end of 2020, there were 209 gigawatts (GW) of wind capacity seeking transmission interconnection, including 61 GW of offshore wind. In 2020, 55 GW of wind capacity entered interconnection queues, 10 GW of which are proposed as hybrid configurations. Energy storage interconnection requests have increased in recent years, both for stand-alone and hybrid plants, most-often pairing solar with storage. The SPP, West (non-ISO), and NYISO regions had the greatest quantity of wind in their queues at the end of 2020. Nearly half of all wind capacity added to interconnection queues in 2020 was for offshore wind plants. vii Land-Based Wind Market Report Industry Trends • GE and Vestas supplied turbines for 87% of U.S. wind power capacity installed in 2020. In 2020, GE captured 53% of the U.S. market for turbine installations, followed by Vestas at 34% and Siemens- Gamesa Renewable Energy (SGRE) at 9%, Nordex at 3%, and Goldwind with 1%.
Recommended publications
  • Weather and Climate: Changing Human Exposures K
    CHAPTER 2 Weather and climate: changing human exposures K. L. Ebi,1 L. O. Mearns,2 B. Nyenzi3 Introduction Research on the potential health effects of weather, climate variability and climate change requires understanding of the exposure of interest. Although often the terms weather and climate are used interchangeably, they actually represent different parts of the same spectrum. Weather is the complex and continuously changing condition of the atmosphere usually considered on a time-scale from minutes to weeks. The atmospheric variables that characterize weather include temperature, precipitation, humidity, pressure, and wind speed and direction. Climate is the average state of the atmosphere, and the associated characteristics of the underlying land or water, in a particular region over a par- ticular time-scale, usually considered over multiple years. Climate variability is the variation around the average climate, including seasonal variations as well as large-scale variations in atmospheric and ocean circulation such as the El Niño/Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO). Climate change operates over decades or longer time-scales. Research on the health impacts of climate variability and change aims to increase understanding of the potential risks and to identify effective adaptation options. Understanding the potential health consequences of climate change requires the development of empirical knowledge in three areas (1): 1. historical analogue studies to estimate, for specified populations, the risks of climate-sensitive diseases (including understanding the mechanism of effect) and to forecast the potential health effects of comparable exposures either in different geographical regions or in the future; 2. studies seeking early evidence of changes, in either health risk indicators or health status, occurring in response to actual climate change; 3.
    [Show full text]
  • Environmental Systems the Atmosphere and Hydrosphere
    Environmental Systems The atmosphere and hydrosphere THE ATMOSPHERE The atmosphere, the gaseous layer that surrounds the earth, formed over four billion years ago. During the evolution of the solid earth, volcanic eruptions released gases into the developing atmosphere. Assuming the outgassing was similar to that of modern volcanoes, the gases released included: water vapor (H2O), carbon monoxide (CO), carbon dioxide (CO2), hydrochloric acid (HCl), methane (CH4), ammonia (NH3), nitrogen (N2) and sulfur gases. The atmosphere was reducing because there was no free oxygen. Most of the hydrogen and helium that outgassed would have eventually escaped into outer space due to the inability of the earth's gravity to hold on to their small masses. There may have also been significant contributions of volatiles from the massive meteoritic bombardments known to have occurred early in the earth's history. Water vapor in the atmosphere condensed and rained down, of radiant energy in the atmosphere. The sun's radiation spans the eventually forming lakes and oceans. The oceans provided homes infrared, visible and ultraviolet light regions, while the earth's for the earliest organisms which were probably similar to radiation is mostly infrared. cyanobacteria. Oxygen was released into the atmosphere by these early organisms, and carbon became sequestered in sedimentary The vertical temperature profile of the atmosphere is variable and rocks. This led to our current oxidizing atmosphere, which is mostly depends upon the types of radiation that affect each atmospheric comprised of nitrogen (roughly 71 percent) and oxygen (roughly 28 layer. This, in turn, depends upon the chemical composition of that percent).
    [Show full text]
  • Wind Energy Forecasting: a Collaboration of the National Center for Atmospheric Research (NCAR) and Xcel Energy
    Wind Energy Forecasting: A Collaboration of the National Center for Atmospheric Research (NCAR) and Xcel Energy Keith Parks Xcel Energy Denver, Colorado Yih-Huei Wan National Renewable Energy Laboratory Golden, Colorado Gerry Wiener and Yubao Liu University Corporation for Atmospheric Research (UCAR) Boulder, Colorado NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. S ubcontract Report NREL/SR-5500-52233 October 2011 Contract No. DE-AC36-08GO28308 Wind Energy Forecasting: A Collaboration of the National Center for Atmospheric Research (NCAR) and Xcel Energy Keith Parks Xcel Energy Denver, Colorado Yih-Huei Wan National Renewable Energy Laboratory Golden, Colorado Gerry Wiener and Yubao Liu University Corporation for Atmospheric Research (UCAR) Boulder, Colorado NREL Technical Monitor: Erik Ela Prepared under Subcontract No. AFW-0-99427-01 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory Subcontract Report 1617 Cole Boulevard NREL/SR-5500-52233 Golden, Colorado 80401 October 2011 303-275-3000 • www.nrel.gov Contract No. DE-AC36-08GO28308 This publication received minimal editorial review at NREL. NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.
    [Show full text]
  • Wind Characteristics 1 Meteorology of Wind
    Chapter 2—Wind Characteristics 2–1 WIND CHARACTERISTICS The wind blows to the south and goes round to the north:, round and round goes the wind, and on its circuits the wind returns. Ecclesiastes 1:6 The earth’s atmosphere can be modeled as a gigantic heat engine. It extracts energy from one reservoir (the sun) and delivers heat to another reservoir at a lower temperature (space). In the process, work is done on the gases in the atmosphere and upon the earth-atmosphere boundary. There will be regions where the air pressure is temporarily higher or lower than average. This difference in air pressure causes atmospheric gases or wind to flow from the region of higher pressure to that of lower pressure. These regions are typically hundreds of kilometers in diameter. Solar radiation, evaporation of water, cloud cover, and surface roughness all play important roles in determining the conditions of the atmosphere. The study of the interactions between these effects is a complex subject called meteorology, which is covered by many excellent textbooks.[4, 8, 20] Therefore only a brief introduction to that part of meteorology concerning the flow of wind will be given in this text. 1 METEOROLOGY OF WIND The basic driving force of air movement is a difference in air pressure between two regions. This air pressure is described by several physical laws. One of these is Boyle’s law, which states that the product of pressure and volume of a gas at a constant temperature must be a constant, or p1V1 = p2V2 (1) Another law is Charles’ law, which states that, for constant pressure, the volume of a gas varies directly with absolute temperature.
    [Show full text]
  • Weather & Climate
    Weather & Climate July 2018 “Weather is what you get; Climate is what you expect.” Weather consists of the short-term (minutes to days) variations in the atmosphere. Weather is expressed in terms of temperature, humidity, precipitation, cloudiness, visibility and wind. Climate is the slowly varying aspect of the atmosphere-hydrosphere-land surface system. It is typically characterized in terms of averages of specific states of the atmosphere, ocean, and land, including variables such as temperature (land, ocean, and atmosphere), salinity (oceans), soil moisture (land), wind speed and direction (atmosphere), and current strength and direction (oceans). Example of Weather vs. Climate The actual observed temperatures on any given day are considered weather, whereas long-term averages based on observed temperatures are considered climate. For example, climate averages provide estimates of the maximum and minimum temperatures typical of a given location primarily based on analysis of historical data. Consider the evolution of daily average temperature near Washington DC (40N, 77.5W). The black line is the climatological average for the period 1979-1995. The actual daily temperatures (weather) for 1 January to 31 December 2009 are superposed, with red indicating warmer-than-average and blue indicating cooler-than-average conditions. Departures from the average are generally largest during winter and smallest during summer at this location. Weather Forecasts and Climate Predictions / Projections Weather forecasts are assessments of the future state of the atmosphere with respect to conditions such as precipitation, clouds, temperature, humidity and winds. Climate predictions are usually expressed in probabilistic terms (e.g. probability of warmer or wetter than average conditions) for periods such as weeks, months or seasons.
    [Show full text]
  • ESSENTIALS of METEOROLOGY (7Th Ed.) GLOSSARY
    ESSENTIALS OF METEOROLOGY (7th ed.) GLOSSARY Chapter 1 Aerosols Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. Air density The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also See Density. Air pressure The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of (atmospheric mercury (Hg) or in hectopascals (hPa). pressure) Atmosphere The envelope of gases that surround a planet and are held to it by the planet's gravitational attraction. The earth's atmosphere is mainly nitrogen and oxygen. Carbon dioxide (CO2) A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid CO2 is called dry ice. Climate The accumulation of daily and seasonal weather events over a long period of time. Front The transition zone between two distinct air masses. Hurricane A tropical cyclone having winds in excess of 64 knots (74 mi/hr). Ionosphere An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist. Lapse rate The rate at which an atmospheric variable (usually temperature) decreases with height. (See Environmental lapse rate.) Mesosphere The atmospheric layer between the stratosphere and the thermosphere.
    [Show full text]
  • HURRICANE IRMA (AL112017) 30 August–12 September 2017
    NATIONAL HURRICANE CENTER TROPICAL CYCLONE REPORT HURRICANE IRMA (AL112017) 30 August–12 September 2017 John P. Cangialosi, Andrew S. Latto, and Robbie Berg National Hurricane Center 1 24 September 2021 VIIRS SATELLITE IMAGE OF HURRICANE IRMA WHEN IT WAS AT ITS PEAK INTENSITY AND MADE LANDFALL ON BARBUDA AT 0535 UTC 6 SEPTEMBER. Irma was a long-lived Cape Verde hurricane that reached category 5 intensity on the Saffir-Simpson Hurricane Wind Scale. The catastrophic hurricane made seven landfalls, four of which occurred as a category 5 hurricane across the northern Caribbean Islands. Irma made landfall as a category 4 hurricane in the Florida Keys and struck southwestern Florida at category 3 intensity. Irma caused widespread devastation across the affected areas and was one of the strongest and costliest hurricanes on record in the Atlantic basin. 1 Original report date 9 March 2018. Second version on 30 May 2018 updated casualty statistics for Florida, meteorological statistics for the Florida Keys, and corrected a typo. Third version on 30 June 2018 corrected the year of the last category 5 hurricane landfall in Cuba and corrected a typo in the Casualty and Damage Statistics section. This version corrects the maximum wind gust reported at St. Croix Airport (TISX). Hurricane Irma 2 Hurricane Irma 30 AUGUST–12 SEPTEMBER 2017 SYNOPTIC HISTORY Irma originated from a tropical wave that departed the west coast of Africa on 27 August. The wave was then producing a widespread area of deep convection, which became more concentrated near the northern portion of the wave axis on 28 and 29 August.
    [Show full text]
  • Climate Change Effects on Wind Speed
    ® Reprinted with permission from the July 2008 issue Climate Change Effects On Wind Speed Predicted changes in wind speeds due to global warming are expected to be modest, but are large enough to affect the profitability of wind projects. BY SCOTT EICHELBERGER, JAMES MCCAA, BART NIJSSEN & ANDREW WOOD oncern about the effects of summer wind power resources of models (i.e., where do the models climate change has been the Northwest U.S. agree on the sign of the change and Cone of the motivating forces According to the study, regional where do they differ?). behind the rapid development of differences in wind speed changes wind energy projects. However, the predicted by different climate mod- Methodology Intergovernmental Panel on Cli- els make it difficult to draw mean- The IPCC has defined a series of mate Change states that “there is ingful conclusions based on the emission scenarios that have been used evidence for long-term changes results from any single GCM simu- as the basis for climate change model- in the large-scale atmospheric cir- lation. Therefore, the projected wind ing studies. These scenarios represent culation, such as a poleward shift speed changes from a large number story lines that provide alternative fu- and strengthening of the wester- of GCMs and for two different emis- ture scenarios. The scenarios do not ly winds” and that these observed sion scenarios are examined herein. have an assigned probability. For this changes likely will continue. Of interest is not just the mean pre- study, model simulations are based on A recent review of historic cli- dictedPercentage change, Ofbut Globalalso the Climatedegree theModels A2 and Showing B1 families Increased of scenarios.
    [Show full text]
  • Wind Speed Effects on Rain Erosivity
    This paper was peer-reviewed for scientific content. Pages 771-776. In: D.E. Stott, R.H. Mohtar and G.C. Steinhardt (eds). 2001. Sustaining the Global Farm. Selected papers from the 10th International Soil Conservation Organization Meeting held May 24-29, 1999 at Purdue University and the USDA-ARS National Soil Erosion Research Laboratory. Wind Speed Effects on Rain Erosivity Katharina Helming* ABSTRACT have based rainstorm kinetic energy values on the terminal The kinetic energy of rainstorms plays a paramount velocity of vertically-falling drops without incorporating the role in surface sealing, runoff, and erosion processes. effect of wind speed on the drop velocity. Only a few studies Typically, the kinetic energy rate is calculated based on have dealt with the relationships between rainstorm terminal velocity of vertically falling raindrops. Few intensity, wind velocity, and rainstorm energy (Disrud, studies have investigated the effect of wind speed on 1970; De Lima, 1990, Pedersen and Hasholt, 1995). raindrop velocity, rainfall energy and on inclination Wind speed affects not only the rainstorm kinetic energy, angles of raindrops. This paper reports an attempt to but also the directional tilt of the raindrops, which in turn determine (i) the effect of wind speed on the kinetic determines the angle of raindrop impact on the soil surface. energy of rainstorms, (ii) the relationships between The degree at which the raindrop makes contact with the soil rainstorm intensity and wind speed, and (iii) raindrop surface is of importance for the compaction and surface impact angle distributions with respect to wind speed, sealing processes, which are predominantly affected by the inclination angle, and soil surface geometries.
    [Show full text]
  • Air Pressure and Wind
    Air Pressure We know that standard atmospheric pressure is 14.7 pounds per square inch. We also know that air pressure decreases as we rise in the atmosphere. 1013.25 mb = 101.325 kPa = 29.92 inches Hg = 14.7 pounds per in 2 = 760 mm of Hg = 34 feet of water Air pressure can simply be measured with a barometer by measuring how the level of a liquid changes due to different weather conditions. In order that we don't have columns of liquid many feet tall, it is best to use a column of mercury, a dense liquid. The aneroid barometer measures air pressure without the use of liquid by using a partially evacuated chamber. This bellows-like chamber responds to air pressure so it can be used to measure atmospheric pressure. Air pressure records: 1084 mb in Siberia (1968) 870 mb in a Pacific Typhoon An Ideal Ga s behaves in such a way that the relationship between pressure (P), temperature (T), and volume (V) are well characterized. The equation that relates the three variables, the Ideal Gas Law , is PV = nRT with n being the number of moles of gas, and R being a constant. If we keep the mass of the gas constant, then we can simplify the equation to (PV)/T = constant. That means that: For a constant P, T increases, V increases. For a constant V, T increases, P increases. For a constant T, P increases, V decreases. Since air is a gas, it responds to changes in temperature, elevation, and latitude (owing to a non-spherical Earth).
    [Show full text]
  • The Relation Between Mantle Dynamics and Plate Tectonics
    The History and Dynamics of Global Plate Motions, GEOPHYSICAL MONOGRAPH 121, M. Richards, R. Gordon and R. van der Hilst, eds., American Geophysical Union, pp5–46, 2000 The Relation Between Mantle Dynamics and Plate Tectonics: A Primer David Bercovici , Yanick Ricard Laboratoire des Sciences de la Terre, Ecole Normale Superieure´ de Lyon, France Mark A. Richards Department of Geology and Geophysics, University of California, Berkeley Abstract. We present an overview of the relation between mantle dynam- ics and plate tectonics, adopting the perspective that the plates are the surface manifestation, i.e., the top thermal boundary layer, of mantle convection. We review how simple convection pertains to plate formation, regarding the aspect ratio of convection cells; the forces that drive convection; and how internal heating and temperature-dependent viscosity affect convection. We examine how well basic convection explains plate tectonics, arguing that basic plate forces, slab pull and ridge push, are convective forces; that sea-floor struc- ture is characteristic of thermal boundary layers; that slab-like downwellings are common in simple convective flow; and that slab and plume fluxes agree with models of internally heated convection. Temperature-dependent vis- cosity, or an internal resistive boundary (e.g., a viscosity jump and/or phase transition at 660km depth) can also lead to large, plate sized convection cells. Finally, we survey the aspects of plate tectonics that are poorly explained by simple convection theory, and the progress being made in accounting for them. We examine non-convective plate forces; dynamic topography; the deviations of seafloor structure from that of a thermal boundary layer; and abrupt plate- motion changes.
    [Show full text]
  • Genesis of Gap Wind Weather Advisory
    April 2004 National Weather Service Volume 3, Number 2 Forecast Process: Genesis of Gap Wind Weather Advisory Colin D. Sells, Meteorologist, Center Weather Service Unit, Anchorage, AK [email protected] On March 30, 1982, 1,780 U.S. In what looked like a safe situa- In this Issue: Army paratroopers from the 82nd tion, 6 jumpers were killed and 158 Airborne Division jumped into drop injured, dragged by winds gusting up Forecast Process: zones at Ft. Irwin. to an estimated 40 mph. Genesis of Gap One of the drop zones was two An investigation concluded the Wind Weather miles long. Before the training jump, two locations where the winds had been Advisory 1 wind measurements were taken at measured were sheltered by high either end of the drop zone. The terrain. In between these points was a Alaska Aviation Weather wind speeds read 7 mph at one end, gap in the mountains. Winds gusted Unit: Providing and 11.5 mph at the other. the maxi- causing what the Army called a “Mass Aviation Weather mum safe wind speed for peacetime Casualty Incident.” Someone had Products and Services training drops was thought to be blundered. to the Alaskan Aviation 14.9 mph. Continued on Page 2 Community 5 When’s the Next Front? Would you like an email when a new edition of The Front is published? Write [email protected] Managing Editor: Michael Graf Contributing Editor: Craig Sanders Editor/Layout: Melody Magnus [email protected] Mission Statement To enhance aviation safety by increasing the pilot’s knowledge of weather systems and processes and National Weather Service products and services.
    [Show full text]